1
2 #include <igraph.h>
3
main()4 int main() {
5 igraph_matrix_t m;
6 igraph_vector_t x, y, z;
7 igraph_real_t xz, xx;
8
9 igraph_vector_init_real(&x, 3, 1.0, 2.0, 3.0);
10 igraph_vector_init_real(&y, 4, 4.0, 5.0, 6.0, 7.0);
11 igraph_vector_init_real(&z, 3, -1.0, 0.0, 0.5);
12
13 igraph_matrix_init(&m, 4, 3);
14 MATRIX(m, 0, 0) = 1;
15 MATRIX(m, 0, 1) = 2;
16 MATRIX(m, 0, 2) = 3;
17 MATRIX(m, 1, 0) = 2;
18 MATRIX(m, 1, 1) = 3;
19 MATRIX(m, 1, 2) = 4;
20 MATRIX(m, 2, 0) = 3;
21 MATRIX(m, 2, 1) = 4;
22 MATRIX(m, 2, 2) = 5;
23 MATRIX(m, 3, 0) = 4;
24 MATRIX(m, 3, 1) = 5;
25 MATRIX(m, 3, 2) = 6;
26
27 /* Compute 2 m.x + 3 y and store it in y. */
28 igraph_blas_dgemv(/* transpose= */ 0, /* alpha= */ 2, &m, &x, /* beta= */ 3, &y);
29 igraph_vector_print(&y);
30
31 /* Compute the squared norm of x, as well as the dor product of x and z. */
32 igraph_blas_ddot(&x, &x, &xx);
33 igraph_blas_ddot(&x, &z, &xz);
34 printf("x.x = %g, x.z = %g\n", xx, xz);
35
36 igraph_matrix_destroy(&m);
37 igraph_vector_destroy(&z);
38 igraph_vector_destroy(&y);
39 igraph_vector_destroy(&x);
40
41 return 0;
42 }
43